JPS6054326B2 - Method for manufacturing polyester containing titanium oxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses crude terephthalic acid without the purification process to produce a titanium oxide-containing polyester in which 80% or more of the repeating structural units are ethylene terephthalate.
The present invention relates to a method for obtaining polyester with excellent quality and process efficiency during fiber production.

Currently, polyethylene terephthalate, which is used in large quantities industrially as fibers or films, undergoes a transesterification reaction and subsequent polycondensation reaction using dimethyl terephthalate (hereinafter abbreviated as DMT) and ethylene glycol (hereinafter abbreviated as EG). It has been manufactured ever since.

This transesterification method is a roundabout method in which terephthalic acid (hereinafter abbreviated as TA) is once reacted with methanol to form DMT, which is then reacted with EG to eliminate methanol again. On the other hand, in order to reduce the cost of raw materials, TA can be used instead of DMT to directly emit carbon dioxide.
The so-called direct polymerization method (direct polymerization method) involves reacting with G or ethylene oxide (hereinafter abbreviated as EO) and producing polyester through an esterification reaction (addition reaction with EO is also considered an esterification reaction) and polycondensation reaction. law) is becoming increasingly popular.

As the TA used in the direct weight method, for example, crude TA obtained by oxidizing P-dialkylbenzene with a molecular oxygen-containing gas is further purified. rough TA
Methods for purifying this include recrystallization from water or other solvents, and oxidation or reduction treatment during the recrystallization process, but all of these methods require a considerable number of steps and are expensive. Therefore, it is difficult to sufficiently reduce the cost of producing polyester. Therefore, rough TA
If it could be used as is for direct loading, it would be possible to significantly reduce costs, but if crude TA were used to produce polymers, the color tone of the polyester would be inferior to that of purified TA, and the whiteness would be poor. The reality is that fiber cannot be obtained.

In recent years, it has become possible to obtain crude TA of relatively good quality by improving the oxidation conditions of P,-xylene, but in this case, the production efficiency during TA production is poor, so it is necessary to reduce the cost sufficiently. cannot be achieved, and the fiber whiteness is lower than that of purified TA.
It is still considerably inferior to the case using . rough TA
The cause of poor color tone of polyester when using TA is due to coloration due to the various impurities contained in the crude TA, or due to thermal decomposition of the impurities or thermal decomposition of the polyester main chain due to the influence of the presence of impurities. Possible substances include colored substances. The present inventors have previously conducted various studies on a method for obtaining polyester with good color tone using crude TA. As a result, the inventors used crude TA having specific optical properties as a raw material and added a specific phosphorus compound. However, it has been found that by carrying out a polycondensation reaction in the presence of an antimony and/or germanium compound catalyst, a polyester with significantly improved whiteness can be produced.

However, when attempting to produce polyester by using the above-mentioned crude TA and using titanium oxide as a quenching agent in the presence of a phosphorus compound, titanium oxide tends to aggregate in the polymerization system, and the polyester product is It was recognized that it existed as a foreign substance.

If such foreign substances exist, for example, when spinning fibers, the spinning filter may become clogged or yarn breakage may occur during spinning, making it difficult to perform stable spinning for a long time. Decreased mechanical and mechanical properties are observed. Therefore, the present invention aims to solve the above-mentioned drawbacks, and as a result of various studies on methods for preventing agglomeration of titanium oxide in the presence of phosphorus compounds using coarse TA, the present inventors have found that fine particulate Silica. By carrying out the polymerization reaction by adding alumina and/or alumina, the dispersibility of titanium oxide is significantly improved, and even when using crude TA, processability during spinning etc. is good, and polyester with excellent whiteness can be produced smoothly. It was discovered that it can be manufactured.

Fine particulate silica and/or
Alternatively, it is known to add alumina, but it is not known to add it to a polymerization system using crude TA in which a phosphorus compound is present.

In addition, for polymerization reaction systems using DMT or purified TA (
Even if it is added, the dispersibility of titanium oxide does not particularly improve, and it is surprising that the dispersibility of titanium oxide is significantly improved in a straight gravity system using crude TA in the presence of a phosphorus compound. The crude TA in the present invention is obtained by mixing 8 g of TA with 10 g of a Par KOH aqueous solution.
340r dissolved in 0ml and measured using a 5d cell
Absorbance at nμ (hereinafter abbreviated as absorbance) is 0.0
6 to 3.0, preferably 0.08 to 2.5.

If the absorbance is less than 0.06, the whiteness will not improve even if a phosphorus compound is added, and if it is more than 3.0, the whiteness will be improved, but the effect is not large, and the whiteness level is low, so it is not suitable for commercial use. Not used. Further, the TA of the present invention is, for example,
Lower aliphatic acids such as acetic acid and propionic acid are prepared by using a cobalt and/or manganese catalyst in particular by the method shown in Japanese Patent Publication No. 35-4963, US Pat. No. 3,139,452, etc. Crude TA obtained by oxidizing P-xylene using monocarboxylic acid as a solvent
is used.

When two or more types of TA are used in combination, the average value of absorbance should be within the range of the present invention.

As the phosphorus compound used in the present invention, C. ．． H and O
A material containing one or more elements selected from the following as a constituent element is used. Those containing other elements are not preferred because the effect of improving whiteness may be insufficient and the processability may be reduced. The phosphorus compound of the present invention is preferably phosphoric acid,
Oxygen acid compounds of phosphorus such as phosphorous acid, hypophosphorous acid, phosphonic acid, phosphinic acid and derivatives thereof are used.

Examples include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, phosphorous acid, trimethyl phosphite, tributyl phosphite, phosphorous acid. Trioctyl, triphenyl phosphite, tricresyl phosphite, hypophosphorous acid, phenylphosphonic acid, dimethyl phenylphosphonate, diphenyl phenylphosphonate, ethylphosphonic acid, diethyl ethylphosphonate, diphenylphosphinic acid, phenyl diphenylphosphinate, etc. There is. When using an antimony compound as a catalyst, it is preferable to add a pentavalent phosphorus compound in order to prevent deterioration of color tone due to reduction of antimony, but a trivalent or lower valent phosphorus compound can also be used if the amount added is small. can.

When using a germanium compound as a catalyst, a phosphorus compound of any valence can be used. The phosphorus compound can be added in any amount, but preferably the amount of phosphorus atoms relative to the weight of the produced polymer (P: Ppm)
(where X represents the absorbance of crude TA) More preferably, the amount used is in a range that satisfies .

If it is added in a smaller amount than the range of formula (1), the whiteness improvement effect will be achieved to some extent, but it will not be sufficient, and even if it is added in a larger amount than the range of formula (1), the whiteness improvement effect will be small and vice versa. This is not preferable because the dispersibility of titanium oxide decreases.

In order to exhibit the effects of the present invention, the timing of addition of the phosphorus compound is determined by [η] (intrinsic viscosity when the polymer is dissolved in a mixed solvent of equal weights of phenol and tetrachloroethane and measured at 30°C, unit: Dt/ y) It is preferably added at a stage before 0.30, and is added at the first stage of the esterification reaction, or at the stage where most of the esterification reaction is completed and the polycondensation reaction is started.

In particular, when a phosphorus compound is added at the beginning of the esterification reaction,
Titanium oxide aggregates significantly, but by adding fine particulate silica and/or alumina according to the present invention, the dispersibility of titanium oxide is greatly improved, making it possible to add the phosphorus compound from the beginning of the reaction, which makes it possible to add fine particles of silica and/or alumina. When TA is used, it is effective in obtaining a polyester with higher whiteness, and is also more preferable from an operational point of view.
The amount of titanium oxide added in the present invention is arbitrary depending on the intended product. Regarding the brand of fiber, in general, based on the weight of the polyester produced, ゜゜Bright is 0.03 to 0.1%, ゜゜Semidal゛ is 0.3 to 0.6%, and ゜゛Fludal゛ is 0.03 to 0.1%. In this case, it is added in an amount of 1.5 to 4%. Titanium oxide is added according to a conventional method from the start of the esterification reaction to the start of the polycondensation reaction under reduced pressure. In particular, according to the present invention, even when added from the beginning of the esterification reaction, the dispersibility is very good. Further, as a dispersibility improver for titanium oxide used in the present invention, fine particulate silica and/or alumina is used.

The particle size used is preferably several microns (μ) or less, more preferably 0.1 μ or less. If the particle size is too large, the effect of improving dispersibility will be small, and the particle itself will become a foreign substance, which will deteriorate spinnability, etc., which is not preferable. Further, even if it is in the form of fine particles, there is no effect even if a substance other than the present invention is added. For example, even if ultrafine titanium oxide is added together with ordinary titanium oxide, the dispersibility will not be improved at all.

The amount of fine particulate silica and/or alumina added is not particularly limited, but usually the larger the amount of the phosphorus compound and titanium oxide added, the larger the amount required. Generally, from 0.001 to the weight of the polyester to be produced.
4.0%, preferably 0.002-2.0% is used. If it is less than 0.001%, the effect of improving the dispersibility of titanium oxide is small, and even if it is added in an amount of 4.0% or more, the effect will not be very large.

Similar to titanium oxide, silica and/or alumina are added from the start of the esterification reaction to the start of the polycondensation reaction under reduced pressure, that is, before the final polymerization reaction begins. It is desirable to add it at the same time as or before titanium oxide, but it may be added after titanium oxide is added if there is not much time lag. Various types of fine particulate silica or alumina are commercially available, but
The fine particles themselves or those dispersed in EG may be used, or those in a colloidal state such as colloidal silica may be used.

The polycondensation catalyst used in the present invention is an antimony compound, a germanium compound, or a mixed system of an antimony compound and a germanium compound.

Other catalyst systems can be used, but generally do not yield polyesters of good color. The polyester in the present invention is a polyester in which 80% or more of repeating structural units are composed of ethylene terephthalate, including isophthalic acid, phthalic acid, adipic acid, sebacic acid, propylene glycol, neopentyl glycol, tetramethylene glycol, 1, 4-cyclohexanedimethanol,
P-oxybenzoic acid, trimethylolpropane, pefuntaerythritol, glycerin, trimesic acid, methoxypolyethylene glycol, naphthoic acid, sodium 3,5-dicarboxybenzenesulfonate, etc. may be copolymerized.

The composition may also contain additives such as polymers such as polystyrene and polyethylene, antioxidants, fluorescent whitening agents, stabilizers, and ultraviolet absorbers. TA<5 as main raw material
When EG is used, a polyester is obtained by carrying out an esterification reaction and then a polycondensation reaction under reduced pressure in a conventional manner.

In addition, when using TA and EO, the first step is to produce bis(β-hydroxyethyl) terephthalate (hereinafter abbreviated as BHET) as the main product, and the first step product is used as a starting material, and the necessary New TA is added according to the conditions, and finally a polycondensation reaction is performed under reduced pressure to obtain a polyester. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In the Examples, 1 part indicating the amount added means all parts by weight. Further, the dispersibility of titanium oxide is [η]0.
I took out the polymer near 5f1', cut it into thin pieces, observed it under a microscope, and found that it was 1T1r! It was expressed as the number of coarse particles with a particle size of 10μ or more in N3. In addition, whiteness refers to [η]0. A durable polymer was extruded from a spinneret into fibers and measured at 450 rT1 using a spectrophotometer with a tungsten light source.
From the reflectances R45O and R55O of μ and 550rT1P polyester fibers, the formula: whiteness (unit, %) =
4R450-3R55. This value was determined using The results of the Examples are collectively shown in Table 1.

Example 1 86 parts of TA with an absorbance of 0.6, 54 parts of EG, 0.5 parts of titanium oxide, and 0.0 parts of antimony oxide as a polymerization catalyst.
3 parts, 0.0 in terms of the amount of phosphorus atom as a phosphorus compound
A polyester synthetic raw material containing 5 parts of tributyl phosphate and 0.1 part of Snowtex O (water-dispersed colloidal silica with a particle size of 10 to 20 rT1μ, manufactured by Nissan Chemical Co., Ltd.) as a dispersion improver was heated at a temperature of 240°C and a pressure of 2.0°C. ~2.5k
g/d for 2 hours while removing the water produced. Then, an esterification (ES) reaction was carried out. Then, the system was brought to normal pressure, and the temperature was raised to 270° C. over three cycles. Subsequently, the system was gradually reduced in pressure (final pressure 20T1rft).
Hg), the temperature was raised to 285°C over 30 minutes, and a prepolymerization reaction was carried out. Further, a polycondensation reaction was carried out at 285° C. under a high vacuum of 17 mHg or less until [η] reached approximately 0.6 fj'. After the polymerization was completed, the polymer was extruded from a spinneret to obtain fibers. Note that during the polymerization, [η] becomes 0. Samples for titanium oxide dispersibility evaluation were collected near the surgical stage. The number of coarse particles was 0 particles/WfL3, and the whiteness was 79%, making it possible to obtain fibers with excellent titanium oxide dispersibility and whiteness using coarse TA.

Comparative Example 1 Polymerization reaction and fiberization were carried out in the same manner as in Example 1 except that Snowtex O was not added, and the number of coarse particles was 1.
Polyester fibers with a whiteness of 77% and a polyester fiber of 2 fibers/Wn3 were obtained.

That is, although the whiteness was good, the dispersibility of titanium oxide was poor. Comparative Example 2 A polymerization reaction was carried out in the same manner as in Example 1 except that tributyl phosphate and Snowtex 0 were not added, and the number of coarse particles was 2/772117!3 and the whiteness was 48%.
of polyester was obtained.

That is, although the titanium oxide dispersibility was quite good, the whiteness was poor. Comparative Example 3 A polymerization reaction was carried out in the same manner as in Example 1 except that tributyl phosphate was not added.
TS! A polyester L3 with a whiteness of 49% was obtained.

That is, the titanium oxide dispersibility was not particularly improved compared to Comparative Example 2, and the whiteness was poor. Comparative Example 4 Purified TA (
The polymerization reaction was carried out in the same manner as in Comparative Example 2 except that the absorbance was 0.04), and the number of coarse particles was 1/TI$L3.
A polyester with a whiteness of 83% was obtained.

Comparative Example 5 A polymerization reaction was carried out in the same manner as in Comparative Example 4, except that Snotex O was added, and a polyester having a coarse particle count of 2/3 and a whiteness of 82% was obtained.

It can be seen from Comparative Examples 4 and 5 that the use of a dispersibility improver in the case of purified TA is rather unfavorable in terms of the number of coarse particles and whiteness. Examples 2 to 7 and Comparative Examples 6 to 11 Absorbance of TA, type and amount of phosphorus compound, and timing of addition (
The polymerization reaction was carried out in the same manner as in Example 1 by changing the amount of titanium oxide, the type and amount of the dispersibility improver, and the polymerization catalyst. Ta.

Titanium oxide and dispersibility improver were each added before the ES reaction. As shown in Table 1, when a dispersibility improver was added, the dispersibility was greatly improved in all cases. In addition, Snowtex N has a particle size of 10 manufactured by Nissan Chemical Co., Ltd.
It was water-dispersed colloidal silica with a particle size of ~20 rnμ, and the amount added was expressed in terms of pure silica content. Aerosil 380 is a fine particle silica with a particle size of about 7 μm manufactured by Kuchimoto Aerosil Co., Ltd., and Thyroid 150 is a fine particle silica with a particle size of 2.2 μm manufactured by Fuji Davison Co., Ltd.
ideC is a particle size of approximately 20rT1 manufactured by Nippon Aerosil Co., Ltd.
It is micro-particle aluminum oxide of μ. Example 8 A mixture of 86 parts of TA with an absorbance of 0.6, 72 parts of EO, and 1 part of triethylbenzylammonium chloride was mixed with 15
Excess EO was removed from the product obtained by reacting at ~22 kg/CltllOO ~120°C for 30 minutes, and then recrystallized once with water and dried to obtain B8CT.

77 parts of this BHET, 36 parts of the TA used above, 77 parts of EG.
3 parts, titanium oxide 0.5 parts, germanium oxide 0.0P
part, 0.05 part of tributyl phosphate, calculated as the amount of phosphorus atom, and Aerosil 200 as a dispersion improver.
A raw material for polyester synthesis consisting of 0.1 part of silica (fine particulate silica, particle size approximately 12rT1μ, Nippon Aerosil Co., Ltd.) was esterified under pressure under the same conditions as in Example 1 until almost no water was produced. Then, in the same manner as in Example 1, the temperature was raised and prepolymerization and final polymerization reactions were carried out to reduce the number of coarse particles to 0/Tn! N3, a polyester with a whiteness of 82% was obtained. Comparative Example 12 A polymerization reaction was carried out in the same manner as in Example 8 except that Aerosil 200 was not added to obtain a polyester having a coarse particle count of 11/7 m3 and a whiteness of 81%.

Example 9 The conditions were the same as in Example 1 except for the amount of the dispersibility improver, and polymerization was carried out in the same manner as in Example 1 to obtain fibers.

In this example, the amount of dispersibility improver is 0.01 part, the number of coarse particles is 0/3, and the whiteness is 78%, resulting in fibers with excellent titanium oxide dispersibility and whiteness. I was able to do that. Example 10 The conditions were the same as in Example 1 except that the amount of the dispersibility improver was 0.003 parts, and polymerization was carried out in the same manner as in Example 1 to obtain fibers.

The number of coarse particles was 1 particle/7m3, so the effect of the dispersibility improver was clear, and the whiteness was 79%, making it possible to obtain fibers with excellent titanium oxide dispersibility and whiteness using coarse TA. . Comparative Example 13 Titanium Oxide instead of Snowtex O
Example 1 except that 02 parts of P25 (fine particulate titanium oxide, particle size approximately 30rT] μ, Nippon Aerosil Co., Ltd.) was added.
The polymerization reaction was carried out in the same manner as above, and the number of coarse particles was 15/T.
A polyester fOlt3 with a whiteness of 78% was obtained.

Claims (1)

[Claims] 1 8 g of terephthalic acid in 100 ml of 2N-KOH aqueous solution
Using terephthalic acid and ethylene glycol, or ethylene glycol and ethylene oxide, which have an absorbance of 0.06 to 3.0 at 340 mμ when dissolved in water and measured using a 5 cm cell, a phosphorus compound is added and in the presence of a catalyst. is subjected to a polycondensation reaction to produce a polyester in which 80% or more of the repeating structural units are ethylene terephthalate, and is characterized by adding fine particulate silica and/or alumina and titanium oxide before the polymerization step. A method for producing polyester containing titanium oxide.